Constant flow rate controller valve

ABSTRACT

A constant flow rate controller valve includes a piston spring biased towards the top of the valve. Fluid or gas flowing into the valve increases the pressure in the chamber above the piston, forcing the piston toward a valve seat. A pin type valve stem is thus seated in the valve seat, blocking gas or fluid flow to the outlet port. The pressure in the chamber below the piston builds until the pressure in this chamber plus the piston spring force is greater than the pressure in the chamber above the piston. The piston then lifts the valve stem from the valve seat, and the pathway to the outlet orifice is opened. Fluid or gas flows through the piston via the caibrated orifice. An equilibrium flow rate is reached by variation in the piston position based on the interaction of the above gas or fluid pressures and spring force.

BACKGROUND OF THE INVENTION

The present invention relates to constant gas or fluid flow regulatorsand more particularly to a flow regulator having a spring biased pistonconnected to a pin valve and being capable of maintaining a constant gasor fluid flow rate in both high pressure, low volume and low pressure,high volume environments with changes in inlet or outlet pressure. Thepresent invention also accommodates high pressure, high volume and lowpressure, low volume systems.

Constant gas or fluid flow regulators capable of accommodating lowpressure, high volume fluid flow often employ sliding sleeves foropening and closing parts of the regulators. Also, multiple poppet typevalves may be used for low pressure, high volume fluid flow regulation.The above prior art, however, generally cannot accommodate highpressure, low volume gas or fluid flow.

This invention, on the other hand, is able to provide constant gas orfluid flow in high or low pressure and high or low volume ranges due tothe low numerical value of the ratio of the surface area of the pinvalve stem to the surface area of the piston within the flow controllervalve.

The present invention is also different from the above sliding sleeveand multiple poppet type valves in that the piston of the valves of theprior art move relative to the valve body to vary fluid flow as thepressure changes, while the piston of applicant's invention does notmove substantially relative to the valve body after fluid flow hasstabilized. Instead, constant spring force on the piston in the presentinvention allows constant flow with changing pressure. The presentinvention thus experiences less wear and tear from moving parts.

Constant fluid flow regulators taught in prior art regulate fluid flowby adjustment screws that directly vary spring tension by attachment tothe piston spring itself. Other regulators change fluid flow by alteringpiston position via springs and ball bearings located over the piston.The system employing springs and ball bearings is subject to extremetorque due to the fluid pressure in the chamber.

The present invention, on the other hand, varies gas or fluid flow byadjustment of the valve seat position, which in turn adjusts pistonspring tension. The change in spring tension thus varies the pressuredifferential across the piston. Torque associated with chamber fluidpressure is thus reduced.

Finally, other constant fluid flow regulators allow fluid flow aroundthe piston periphery to constitute the principal channel of fluidpassage through the regulator. In the high pressure, low flow embodimentof the present invention, the sole flow passage is a single orifice orgroup of orifices through the piston. This calibrated flow orifice, ororifices, allows precise measurement and calculation of prospective flowrates, unavailable in most of the prior art devices. The use of the soleflow path in one of the applicant's embodiments allows the valve tofunction at high pressure, unlike the prior art. Fluid flow around thepiston periphery in the prior art prevents use in high pressure, lowfluid environment.

SUMMARY OF THE INVENTION

The present invention provides a mechanism for automatically maintaininga uniform rate of gas or fluid flow through a flow channel under varyingpressures from gas or fluid sources. In accordance with the presentinvention, a valve body has an inlet port and a single outlet portthrough the valve body. A bore is located within the valve body. Apiston is disposed within the bore and is biased with a spring orsprings. The piston divides the bore into two channels. The flow paththrough the valve mechanism is a calibrated flow orifice or orifices.The piston is connected to a pin type valve stem by a spring. The pintype valve stem seals with a seat.

The piston is initially spring biased towards the top portion of thevalve. Fluid or gas flowing into the controller valve via the inlet portincreases the pressure in the chamber above the piston, forcing thepiston toward the valve seat. The pin type valve stem is thus seated inthe valve seat, blocking gas or fluid flow to the outlet port. Thepressure in the chamber below the piston builds until the pressure inthis lower chamber plus the piston spring force is greater than thepressure in the chamber above the piston. The piston then lifts thevalve stem from the valve seat, and the pathway to the outlet orifice isopened. Fluid or gas flows through the piston via the calibratedorifice. An equilibrium flow rate is reached (i.e., when the pressure inthe upper chamber equals the pressure in the lower chamber plus thespring force) by variation in the piston position based on theinteraction of the above gas or fluid pressures and spring force.

After the desired flow rate has been attained, the piston no longermoves substantially relative to the valve body. Instead, constant flowrate is maintained despite pressure changes because the spring forcemaintains a constant pressure differential between the two valvechambers.

DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention may be had by reference tothe accompanying drawing illustrating a preferred embodiment of theinvention to be described in detail, wherein:

FIG. 1 is a cross-sectional view of a valve mechanism in accordance withthe present invention; and

FIG. 2 is a schematic view of the valve mechanism as used in anexemplary injection system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The novel features believed to be characteristic of this invention areset forth in the appended claims. The invention itself, however, maybest be understood and its various objects and advantages bestappreciated by reference to the detailed description below in connectionwith the accompanying drawings.

Referring to FIG. 1, the reference numeral 10 indicates the constantflow rate controller valve, as a whole. Valve 10 has a valve body 12having at its top portion an inlet port 14, and having at its bottomportion an outlet port 16. A bore 18 is formed within valve body 12; thebore 18 is defined by an elongated cylinder of decreased diameter at itslower portion.

A piston 20 having a head 21 is disposed within bore 18 such that aportion of bore 18 is divided into chamber 22 above piston head 21 andchamber 24 below piston 20. Piston 20 is of a generally cylindricalconfiguration. Chambers 22 and 24 are sized to be of relatively smallarea to minimize the amount of "fluid packing" in the invention. "Fluidpacking" relates to the amount of fluid in the valve. If less flow ispresent in the valve, fluid compressability will not delay the responsetime of the valve to presure fluctuations.

When applicant's device is used in a high pressure, low volumeenvironment (e.g., 5000 p.s.i. and 0.5 gallons per day), the sole flowpath through the constant flow rate controller valve 10 is an axial flowpath through the piston 20. No other paths are present, such as fluidflow around the periphery of piston 20, thus allowing the invention tooperate in high pressure, low flow environments. However, for use in alow pressure, high flow environment (e.g. 20 p.s.i. and 100 gallons perday), fluid flow around the periphery of piston 20 may occur. This axialflow path within piston 20 is an orifice 26 that permits the flow offluid or gas from chamber 22 through piston 20 and into chamber 24.However, orifice 26 need not pass through piston 20, but may connectchamber 22 and 24 by passing through valve housing 12 instead.

In order to prevent fluid or gas flow around the periphery of piston 20when this invention is employed in high gas or fluid pressureenvironments, seal 28 is placed around the periphery of piston 20. Seal28 is preferably a cup seal. Seal 28 is optional when the invention isused in a low pressure environment. When used in a low pressureenvironment, seal 28 may be a diaphragm seal.

Within chamber 24 are springs 30 which contact piston 20 and bias piston20 upwardly toward chamber 22. Springs 30 may specifically be Bellvillewasher type springs, manufactured by Key Bellville, Inc., Box 1916,Leechburg, Pa. 15656, may be another washer type spring, or may beanother type of spring, such as a coil type spring for example. Byemploying washer type springs for springs 30, the desired flow rate maybe conveniently altered by stacking additional washer type springs tovary the spring force present in chamber 24 of the constant flow ratecontroller valve 10, thus changing the pressure differential across thepiston.

Piston shaft 32 is a relatively narrowed cylindrical structure locatedon the bottom portion of piston 20. Internal piston chamber 34 is a boreof a first relatively narrow diameter within piston shaft 32, and of asecond relatively broader diameter within piston 20. Located withininternal piston chamber 34 is spring 36. Also located within internalpiston chamber 34 is a pin valve having a pin valve stem 38, which isbiased downward by spring 36 such that the bottom end of pin valve stem38 protrudes from internal piston chamber 34 and piston shaft 32. Pinvalve stem 38 is shaped and sized to complement the above stated varieddiameter of internal piston chamber 34. Note that other,. types andshapes of valve plugs besides a pin valve may be employed provided thatthe surface area of the valve plug is substantially less than thesurface area of the piston (e.g., 0.03 inches in plug diameter comparedto 1.5 inches in piston diameter) so that the valve 10 can functionindependently from the flow pressure at the outlet port 16, as describedbelow. For example, a ball-type valve plug may also be employed. Thebottom end of pin valve stem 38 has a small surface area, and is conicalin shape to incrementally vary the flow rate of the fluid exitingchamber 24 to achieve the desired initial flow rate, as detailed morefully below.

The bore 18 forming chamber 22 and 24 is sized such that the diameter ofbore 18 below chamber 24 is substantially narrower than the portions ofbore 18 forming chambers 22 and 24. This narrowed portion of bore 18,exit channel 42, is sized to accomodate piston shaft 32 as piston 20 isforced toward exit channel 42 when the fluid or gas pressure in chamber22 is greater than the fluid or gas pressure and the spring force inchamber 24.

Sized to fit within exit channel 42 is pin valve seat 40, which is alsosized to seat pin valve stem 38. Note that if pin valve stem 38 seats inpin valve seat 40 with excessive force, spring 36 prevents structuraldamage by absorbing this excessive force. Fluid path 46 is an axial flowpath within pin valve seat 40, which accomodates gas or fluid flow fromchamber 24 to outlet port 16 when pin valve stem 38 is not seated in pinvalve seat 40. Fluid path 46 is of a substantially narrower diameterthan exit channel 42 to minimize "fluid packing," as discussed above.

Gas or fluid flow rate may be varied by adjustment of adjustment screw48, which contacts the bottom portion of pin valve seat 40 and variesthe position of pin valve seat 40 within exit channel 42. The forceexerted by springs 30 may thus be increased or decreased because thechange in position of pin valve seat 40 changes the distance piston 20must travel to seat pin valve stem 38 in pin valve seat 40. In thismanner, the change in spring tension of spring 30 varies the springforce on piston 20, thus varying the pressure differential betweenchamber 22 and chamber 24. Adjustment screw 48 is machined to allowmaximum to minimum flow rate within one 360 degree turn of adjustmentscrew 4.

The constant flow rate controller valve 10 operates based on thefollowing force balance equations:

    P.sub.1 ·A.sub.piston =(P.sub.2 ·A.sub.piston)+KX+(A.sub.pin. P.sub.out)

Where

P₁ =pressure in chamber 22

A_(piston) =surface area of piston 20

P₂ =pressure in chamber 24

KX=spring force of springs 30

A_(pin) =surface area of pin valve stem 38 which mates with seat 40

P_(out) =pressure at outlet port 16

Rearrangement of terms produces the equation

    P.sub.1 -P.sub.2 /A.sub.piston =KX+(A.sub.pin ·P.sub.out)

Because A_(pin) is negligible in comparison to A_(piston), and assumingP₂ equals the flow pressure at outlet port 16, the following equationcharacterizes the force balance existing in the present invention.

    P.sub.1 -P.sub.2 /A.sub.piston =KX

Thus, the differential pressure (P₁ -P₂) is a function of spring force(KX).

The flow rate of water, for example, through the constant flow ratecontroller valve 10 is defined by the following equation:

    q=20.sup.· (P.sub.1 -P.sub.2)/R

Where

q=flow rate

P₁ =pressure in chamber 22

P₂ =pressure in chamber 24

R=flow resistance across orifice 26

Note that because differential pressures (P₁ -P₂) is a function ofspring force (KX), flow rate (q) is also a function of spring force.Thus, the constant flow rate controller valve 10 has a constant flow aslong as spring force remains constant. This flow is constant regardlessof the flow pressure at inlet port 14. Theoretically, there is apressure force exerted on the pin valve stem 38 and against the piston20 defined by

    P.sub.out ·A.sub.pin

Where

P_(out) =pressure at outlet port 16

A_(pin) surface area of pin valve stem 38,

However, the above force is negligible due to the small surface area ofpin valve stem 38 when compared to the surface area of piston 20. Thus,flow rate is constant regardless of the flow pressure at outlet port 16.Note that this force would not be negligible and the flow rate would notbe constant if, in the present invention, the area of the pin valve stem38 was not small in value when compared to the surface area of piston20.

The constant flow rate controller valve 10 operates as follows. Gas orfluid passes though inlet port 14 and enters chamber 22. Piston 20,which is biased by springs 30 towards chamber 22, is pushed towardchamber 24 by the increased pressure in chamber 22, thus seating pinvalve stem 38 in pin valve seat 40. The seating of pin valve stem 38 inpin valve seat 40 blocks flow to flow path 46 and outlet port 16.Chamber 24 is thus sealed.

Gas or fluid flows from chamber 22 into chamber 24 via orifice 26, andthe flow pressure in chamber 24 increases.

When the flow pressure in chamber 24 plus the spring force of spring 30exceeds the pressure in chamber 22, piston 20 is pushed towards chamber22 and pin valve stem 38 is unseated from pin valve seat 40. A pistonequilibrium position is next attained when the flow pressure in chamber22 equals the flow presure in chamber 24 plus the spring force of spring30.

The above piston equilibrium position also provides the desired flowrate. Without further substantial change in the position of piston 20,the flow rate will remain constant despite flow pressure changes becausethe spring force of springs 30 maintains a constant pressuredifferential between chamber 22 and chamber 24.

Referring to FIG. 2, an exemplary injection system employing applicant'sconstant flow rate controller valve 10 is shown. This injection systemmay be, for example, a food production system in which minute quantitiesof vitamins, flavorings, colorings, additives, preservatives or the likemust be added to a food product flow path at a constant rate in a highpressure, low volume environment.

Specifically, a single metering pump services a multi-location injectionsystem with numerous injection points. On a single line from the pump, avariety of informational and/or regulational devices may be placed, suchas a pulsation damper, pressure gauge and a back pressure regulator.This single line is then split into a series of process injection lines,each of which services a particular process injection point. Attached toeach of these individual process injection lines is a shut off valve, afilter and applicant's constant rate flow controller valve 10. Thenumber of valves 10 that may be employed in the system of FIG. 2 islimited by the pump strength. Note that no additional energy source isrequired for operation of applicant's constant rate flow controllervalve 10. Valve 10 operates solely on the differential pressure betweenthe inlet 14 and outlet 16, as shown in FIG. 1.

While particular embodiments of the present invention have beendescribed in some detail above, changes and modifications may be made inthe illustrated embodiments without departings from the form or spiritof the invention. It is therefore intended that follwing claims coverall equivalent modifications and variations as fall within the scope ofthe invention as defined by the claims.

I claim:
 1. A valve mechanism for regulating gas or fluid flowcomprising:a housing having an inlet and outlet forming a flow passagethrough said housing; a piston mounted in a bore formed in said flowpassage, said piston intersecting said flow passage, said pistondividing a portion of said flow passage into first and second chamberslocated at opposite sides of said piston and respectively communicatingwith said inlet and outlet; an orifice through said piston, said orificeconnecting said first and second chambers, said orifice calibrated for apredetermined flow rate and being the sole gas or fluid flow passagefrom said inlet to said outlet; a valve stem connected with said pistonfor movement therewith by a first spring means, said valve stem having asmall surface area in relation to the surface area of said piston; avalve seat between said piston and said outlet, said valve seat alignedto seat and unseat said valve stem based on the relative position ofsaid piston within said housing; a second spring means biasing saidpiston toward said inlet, said spring means providing a bias force thatestablishes a substantially constant pressure differential between saidfirst chamber and said second chamber to enable a substantially constantoutlet flow at varied pressures without substantial movement of saidpiston after flow is initiated; and, a screw adjustment means in contactwith said valve seat, said valve seat being variable in position withinsaid housing based upon adjustment of said screw adjustment means.
 2. Avalve mechanism for regulating gas or fluid flow comprising:a housinghaving an inlet and an outlet forming a flow passage through saidhousing; a piston mounted in a bore formed in said flow passage, saidpiston intersecting said flow passage, said piston dividing a portion ofsaid flow passage into first and second chambers, said chambers locatedat opposite sides of said piston and respectively communicating withsaid inlet and outlet; orifice means providing a calibrated rate of gasor fluid flow between said first and second chambers; a valve stemconnected to said piston by a first spring means, said valve stem havinga surface area which is small in relation to the surface area of saidpiston; a valve seat between said piston and said outlet, said valveseat aligned to seat and unseat said valve stem based on the position ofsaid piston relative to said housing; a second spring means biasing saidpiston toward said inlet, said second spring means providing a biasforce that establishes a substantially constant pressure differentialbetween said first chamber and said second chamber such that asubstantially constant flow is produced at said outlet withoutsubstantial movement of said piston and without substantial additionalmovement of said valve stem relative to said valve seat after flow isinitiated, whereby the flow rate remains substantially constant atvaried pressures; and means for varying the flow rate by adjusting saidbias force exerted by said second spring means by varying the positionof said valve seat in order to adjust the flow rate.
 3. The valvemechanism of claim 2 wherein said orifice is the sole gas or fluid flowpassage from said inlet to said outlet.
 4. The valve mechanism of claim3 further comprising sealing means between said piston and said housingto prevent flow peripheral to said piston.
 5. The valve mechanism ofclaim 2 wherein said second spring means is a washer type spring.
 6. Thevalve mechanism of claim 2 wherein said means for adjusting said forceexerted by said second spring means is a screw in contact with saidvalve seat.
 7. A valve mechanism for regulating gas or fluid flowcomprising:a housing having an inlet and outlet forming a flow passagethrough said housing; a piston mounted in a bore formed in said flowpassage, said piston intersecting said flow passage, said pistondividing a portion of said flow passage into first and second chambers,said chambers located at opposite sides of said piston and respectivelycommunicating with said inlet and outlet; an orifice through saidpiston, said orifice connecting said first and second chambers, saidorifice calibrated for a predetermined flow rate and being the sole gasor fluid flow passage from said inlet to said outlet; a valve stemconnected with said piston by a first spring means, said valve stemhaving a small surface area in relation to the surface area of saidpiston; a valve seat between said piston and said outlet, said valveseat aligned to seat and unseat said valve stem based on the relativeposition of said piston within said housing; a second spring meansbiasing said piston toward said inlet; and, a screw adjustment means incontact with said valve seat, said valve seat being variable in positionwithin said housing based upon adjustment of said screw adjustmentmeans.
 8. A valve mechanism for regulating gas or fluid flowcomprising:a housing having an inlet and an outlet forming a flowpassage through said housing; a piston mounted in a bore formed in saidflow passage, said piston intersecting said flow passage, said pistondividing a portion of said flow passage into first and second chamberslocated at opposite sides of said piston and respectively communicatingwith said inlet and outlet; orifice means providing a calibrated rate ofgas or fluid flow between said first and second chambers; a pressureregulating valve disposed within said flow passage between said pistonand said outlet, controllable by said piston, and including a valve plugand valve seat; a first spring means connecting said piston to saidvalve plug; and a second spring means biasing said piston only towardsaid inlet, said second spring means cooperating with said piston andpressure regulating valve to establish a substantially constant pressuredifferential between said first chamber and said second chamber suchthat a substantially constant flow is produced at said outlet withoutsubstantial movement of said piston after flow is initiated. means forvarying the flow rate by adjusting the bias force exerted by said secondspring means by varying the position of said valve seat in order toadjust the flow rate.